Japanese Unexamined Patent Publication No. 2001-209406 (patent document 1) describes a PLC simulator device for simulating an instruction execution of a PLC (Programmable Logic Controller) program. The PLC program is specifically a sequence program described with languages such as ladder diagram or instruction list. The PLC simulator device executes the PLC program for every instruction execution and displays the execution result. The debugging of the PLC program is thus facilitated.
Patent Document 1: Japanese Unexamined Patent Publication No. 2001-209406